Increasing the RF 433 Mhz transmitter range
I am trying to design a RF transmitter using the saw resonator for 433 Mhz. I have got it to work but at a very small distance. I am trying to make it work for around 50-60 meters. My circuit is similar to the attachment, but values are somewhat different.
R1 : 50 K , no R2, L2 .
C3: 5pF, C4: 18pF.
I want to increase the transmitting distance, if anyone who can help.
Regards
Sanket
Hi there sanket
welcome to the forums
what antenna are you currently using ?
do you need omni-directionality or could you use a directional antenna ... say a 3 element yagi
does it have to be totally portable ?
Is antenna size an issue ?
Is the transmitter able to be modified to add another amplifier stage ?
what is that current transistor ?, what is the output of the transmitter supposed to be ?
answer those questions and then some good suggestions could be given
and you shouldn't omit The L2 inductor
cheers
Dave
Hi davenn
I am trying to build a small remote control, so antenna size is an issue. Currently my inductor acts as an antenna. I cannot modify the transmitter for another amplification stage. The transistor I am using is BFS17A rf transistor.
The output of the transistor is an encoded signal from an encoder IC.
I am trying to build it for small remote control as used in cars so size is an issue.
1st check output power, and supply current. The collector should be twice the supply voltage p-p when On. Can you increase power with battery voltage?
. Then fix coupling cap to antenna with a much smaller value to tune impedance to antenna and resonate at 450MHz. L2 is required for this.
what is the load impedance for Saw filter?